Minimal API wrapper around the MustangProject validator.
When issuing or receiving electronic invoices, it is a good idea to validate them against the corresponding schemas. One software that you can use for this purpose is MustangProject which comes with a CLI.
The problem with the CLI is that it starts up very slowly and can validate only one document at a time. This server offers the validation features of MustangProject as a minimal server API. This allows performant batch validation of invoices.
It also avoids privacy issues because the invoices do not have to be sent over the internet to third-party services.
This project is a sister project of E-Invoice-EU. See there for information about how to create electronic invoices.
Download a validator-VERSION-jar-with-dependencies.jar file from the
releases page.
Then run the server
PORT=8080 java -jar target/validator-2.21.0-jar-with-dependencies.jar
Inspect the sources if you want to run a jar file without dependencies.
mvn clean install
PORT=8080 mvn compile exec:java -Dexec.mainClass=com.cantanea.validator.App
The service has one single endpoint /validate. It takes one single URL
parameter invoice that contains the invoice file.
curl -v -X POST -Finvoice=@invoice.xml http://localhost:8080/validate
This would validate the invoice in the file invoice.xml. The hybrid
formats Factur-X resp. ZUGFeRD can also be validated:
curl -v -X POST -Finvoice=@invoice.pdf http://localhost:8080/validate
If the document is valid, you will receive a response with a status code of 200. For invalid documents, 400 is sent.
The output is an XML validation report, for example:
<?xml version="1.0" encoding="UTF-8"?>
<validation filename="invoice.xml" datetime="2025-04-25 13:36:39">
<xml>
<info>
<version>2</version>
<profile>urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0</profile>
<validator version="2.16.4"/>
<rules>
<fired>13</fired>
<failed>0</failed>
</rules>
<duration unit="ms">776</duration>
</info>
<summary status="valid"/>
</xml>
<summary status="valid"/>
</validation>
For the hybrid Factur-X/ZUGFeRD formats, you will see three summaries; the first one for the PDF validation, the second one for the validation of the embedded XML, and the third one for that overall status:
<?xml version="1.0" encoding="UTF-8"?>
<validation filename="invoice.pdf" datetime="2025-04-25 14:36:22">
<pdf>ValidationResult [flavour=3b, totalAssertions=6686, assertions=[], isCompliant=true]
<info>
<signature>unknown</signature>
<duration unit="ms">1723</duration>
</info>
<summary status="valid"/>
</pdf>
<xml>
<info>
<version>2</version>
<profile>urn:cen.eu:en16931:2017#conformant#urn:factur-x.eu:1p0:extended</profile>
<validator version="null"/>
<rules>
<fired>69</fired>
<failed>0</failed>
</rules>
<duration unit="ms">1217</duration>
</info>
<summary status="valid"/>
</xml>
<summary status="valid"/>
</validation>
The versions of this package follow that of MustangProject. In other words, when you are using version 2.16.4 of this package, it uses MustangProject version 2.16.4 under the hood.
Copyright (C) 2025 Guido Flohr guido.flohr@cantanea.com, all rights reserved.
This is free software available under the terms of the WTFPL.
This free software has been written with the greatest possible care, but like all software it may contain errors. Use at your own risk! There is no warranty and no liability.